The present invention relates to control systems for a motor vehicle chassis, and more particularly to a system and method including a feedforward feature for controlling the chassis.
Unified or integrated chassis control systems have been proposed which control the brakes, steering, and suspension of a motor vehicle. The purpose of unified chassis control is to improve vehicle performance in all driving conditions by coordinating control of the chassis subsystems. Unified chassis control systems typically utilize a supervisory control concept that utilizes three fundamental blocks: a reference model, a state estimator, and a vehicle control. The vehicle control element normally incorporates a feedback control. This element computes control values by comparing actual states obtained from the state estimator with desired states from the reference model.
It is well known that when brakes are applied during a steering maneuver, a yaw rate error is induced. It such circumstances, the conventional chassis control systems are relatively slow to compensate.
The present invention is a system and method for controlling a plurality of motor vehicle chassis subsystems. The control system comprises a reference model, a state estimator, a feedforward controller, and a feedback controller. The reference model computes desired states of the chassis subsystems. The state estimator estimates actual states of the vehicle. The feedforward controller computes a control value based on the reference model, and the feedback controller computes a control value by comparing the estimates of actual states with the desired states.
Accordingly, it is an object of the present invention to provide a control system of the type described above which presents a standard methodology to integrate feedforward control into a unified chassis control supervisor that overcomes several known deficiencies.
Another object of the present invention is to provide a control system of the type described above which improves control response.
Still another object of the present invention is to provide a control system of the type described above which improves response decoupling.
Still another object of the present invention is to provide a control system of the type described above which allows single-point tuning.
Still another object of the present invention is to provide a control system of the type described above which incorporates driver input.
The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.